We demonstrate optical limiting for the C(60) fullerene in polymethyl methacrylate (PMMA) as a solid polymer host. It is shown that the optical-limiting behavior is consistent with excited-state absorption (reverse saturable absorption) as a mechanism. We suggest that a higher threshold for optical limiting compared with that of C(60) in toluene is due to nonlinear scattering for the liquid. The performance of C(60) in PMMA is compared with that in chloroaluminum phthalocyanine, N-methylthioacridone, King's complex, and ruthenium King's complex in PMMA. Optical damage thresholds are reported.

an increase in &3"". The k2 term probably does not give a large contribution since the linear correlation shown for pyrrolidine in Figure 4 is only possible if k2 is negligible, and this term should not be greatly affected by the structural change that is involved in going from the secondary amine to the investigated primary amines. Also, at the lower amine concentrations the first portion of the plot reported in Figure 3 for pyrrolidine is approximately linear, a condition that can only be possible if k.x > k2 +

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A method for studying solvation of styrene-divinylbenzene copolymers is described. Styrene-divinylbenzene copolymers doped with derivatives of 5-(dimethylamino)-1 -naphthalenesulfonamides were prepared. The fluorescence emission spectra of the copolymers were recorded in a variety of solvents. Comparisons of these data with the fluorescence emission of the probe molecule in pure solvent were used to provide information regarding copolymer solvation.Chemical reactions of functionality embedded in highly cross-linked polymers take place at the solvent-polymer interface. These reactions involve an interplay between polymer-bound functionality, homogeneous reagents, and solvents that vary in their ability to solvate pendent polymer chains.1 Reactivity of functionality embedded in less highly cross-linked polymers is further influenced by the solvent's ability to swell the gel, thereby permitting access to the interior of the gel particle.

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